Hm, it may be a good idea. However, working in a separate thread won't solve all the issues (see [the hacking doc regarding thread safety](https://github.com/jflesch/paperwork/blob/testing/HACKING.markdown#thread-safety)). So I think it will depend of the time required to refit&predict them all (we are talking about many hundred of documents here).

Anyway, I think we should merge your current changes as is in jflesch/paperwork/unstable. You can send later another pull request to do the refit&predict at start. This way, we will both be able to clearly see the difference.